Construction And Research Of Flexible Nanofiber-based Electronic Skin

Artificial electronic skin must be a flexible sensor.It should detect different mechanical forces,such as pressure,strain,and bending.It should also have soft elasticity to cover any irregular surfaces and linear weavability for integration into the textile.Previous studies have described flexible pressure sensors built on nanometer-materials?nanowires,carbon nanotubes,polymer nanofibers,metal nanoparticles,and graphene?as well as stretchable strain sensors based on stretchable materials and new architectures.However,the practical application of these pressure sensors in continuous and real-time monitoring are quite limited due to the lack of flexibility.Therefore,it is a challenge that developing multimodal mechanical sensors capable of realizing real-time monitoring as well as facile integration,weavability,and high performance.The main work of this paper is as follows:?1?First,continuous PAA/PU nanofiber yarns were prepared via electrospinning technology.Conductive polypyrrole?PPy?was then coated on the surface of the nanofibers via in-situ polymerization,and a high-elastic strain sensor based on PAA/Pu@PPy yarn was constructed.The stretching sensing properties of the sensor was tested.The tensile strain sensing performance of the strain sensor was studied.The strain sensor has excellent tensile strain sensing performance?the tensile sensitivity factor is 21.6?,and in wearable electronics applications,it can detect large strains of multi-directional forces,such as joints and wrist flexing,and tiny movements,such as facial muscles.?2?First,continuous graphene oxide?GO?-doped polyacrylonitrile?PAN?nanofiber yarns were prepared via electrospinning technology.Conductive polypyrrole?PPy?was then coated on the surface of the nanofibers via in-situ polymerization.The resulting conductive nanofiber yarns were further wound on the elastic yarns to form composite yarn?GCNF@ECY?.The resulting GCNF@ECYs were then woven into a fabric to obtain a fabric-like sensor.As a fabric-like electronic skin,it can monitor mechanical forces induced by pressure,strain,and bending over a wide range.This exhibits high sensitivity(pressure sensitivity and GF are approximately 4.08 N^–1and 68,respectively).Furthermore,the GCNF@ECY sensor unit has a large workable strain range?¹00%?and a small strain detection limit of0.1%.The high sensitivity of the fabric-like electronic skin is attributed to the hierarchical construct in the fabric that ranged from the macroscopic yarn to the submicron-scale fibers to the nanometer-scale particles.The multimodal mechanical sensing performance is related to the wrapped structure that winds the conductive nanofiber yarn on the elastic yarn.In addition,this fabric-like sensor displayed superior performance for monitoring human health?pulse and breathing?and a full range of human motion?facial expressions,joints,and nape?.